The present invention pertains to a process of making alcohol-free beer.
Beer is a fermented beverage whose origin goes far back in time. Beer is principally made from barley malt and is highly valued for its savour and its plentiful foam. Additional on the subject of beer can be found in encyclopedias such as Ullmann's Encyclopedia (Ullman's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. 4, p. 421) or the Kirk-Othmer Encyclopedia (Encyclopedia of Chemical Technology, 3rd Edition, Vol 3, p. 692). It can be stated very schematically for the present purpose that beer is a beverage which is rich in fixed or volatile aromatic substances and in alcohol. For various legal, dietary, cultural and even religious reasons, there is interest in the production of alcohol-free and low-alcohol beers. The technical objective has been established to ferment beers which despite their low final content of alcohol will preserve their organoleptic properties.
Normal beers ordinarily contain 4 to 8% alcohol but some contain more than 10% and others barely exceed 2%. Opposed to them are low-alcohol beers that contain circa 2% alcohol, very-low-alcohol beers (0.5 to 1%), alcohol-free beers that must contain less than 0.5% alcohol, and alcohol-free malt beverages containing less than 0.05% alcohol. Only the last two types are considered by the law to be alcohol-free beverages.
Diverse techniques have been employed to achieve the objective of beers containing little or no alcohol such as fermentation (European Patent Application 213,220) which is stopped before the alcohol level becomes too high (however, by blocking the formation of alcohol there is also a reduction in the production of the aromas specific to beer); fermentation using strains selected to not produce alcohol (European Patent Application 245,841); distillation (Cysewski, G. R. et al., Biotech. Bioeng. 1976, 18, 1297; 1977, 19, 1125) by means of which the alcohol is eliminated by heating the beer which simultaneously degrades the protein components and the sugars; membrane separation (Cysewski G. R. et al, Biotech. Bioeng. 1978, 20, 1421) and its variants comprising reverse osmosis (U.S. Pat. No. 4,317,217); and pervaporation (European Patent Application 332,738) which nevertheless leaves from 1 to 1.5% of alcohol in the final product and which involves very delicate application techniques.
The production of alcohol from aqueous alcoholic solutions via extraction with hydrophobic adsorbents, more specifically hydrophobic silicas or hydrophobic zeolitic silico-aluminates, is disclosed in European Patent Application No. 101,254. The adsorbents employed for the application of this procedure are zeolites with an Si:Al ratio higher than 12 and notably zeolites such as those obtained in accordance with the procedure described in French Patent No. 2,567,868 (CFR) .beta.-zeolites, silica-rich offretites (French Patent 2,575,741) or the USY zeolites with an Si:Al ratio higher than 12 that Bibby and Milestone (J. Chem. Tech. Biotechnol. 1981, 31, 732) discovered were suitable for the extraction of molecules dissolved in water, but less polar than water. It might appear attractive to transpose the principle of this technique to the fabrication of alcohol-free beverages. In addition, Farhadpour (Eur. Brew. Conv. 1983, 12, pp. 203-217, then Processing, Sept. 1987, p. 42) has proposed the extraction of alcohol from beer by adsorption on a very closely related adsorbent, a hydrophobic silica (silicalite).
It is certainly possible to obtain beer containing little or no alcohol with these various techniques, but the fermentation processes that generate little alcohol also generate few aromas and, in terms of the dealcoholization processes, it is not possible to extract the alcohol without an at least partial loss of aromas and it is frequently necessary to readjust the flavors of the product in the final stage, e.g., by means of aromas extracted from yeasts (French Patent 2,106,755).